Abstract
What are the main findings? Two new lead quinoxaline derivatives promote measurable auditory supporting cell proliferation and the generation of new sensory hair cells in zebrafish neuromasts and mouse organs of Corti without inducing apoptosis or impacting the function of the sensory hair cells. Improved hearing in mice at certain treatment doses, along with observed proliferation patterns, indicates compound-specific effects and suggests the engagement of canonical pro-growth pathways, including Wnt/β-catenin and MAP3K1-IKK-NF-κB. What are the implications of the main finding? Enhancing the proliferation of auditory supporting cells through pharmacological modulation could improve the mitotic regenerative capacity of mammalian sensory epithelia, ultimately creating more favorable conditions for future strategies aimed at regenerating auditory hair cells. These findings highlight two quinoxaline derivatives as promising candidates for further exploration into their role in treatment pathways, long-term safety, and potential use in regeneration-based strategies for sensorineural hearing loss. No pharmacological interventions exist that can restore or preserve auditory function in the mammalian cochlea. Auditory hair cells (HCs) do not spontaneously regenerate, leading to permanent hearing loss. In non-mammalian vertebrates, HC regeneration happens through proliferation and differentiation of their clonally related supporting cells (SCs). The present study supports the potential of quinoxaline (Qx), a nonsteroidal anti-inflammatory compound, to stimulate SC proliferation in the auditory sensory epithelium, a process that may prime the tissue for future HC regeneration. We synthesized a series of Qx derivatives by introducing various substitutions, ranging from hydrophilic to lipophilic. Seventy analogs were generated and tested in vitro and in vivo. Among those, only one (Qx-100) exhibited the best medicinal chemistry profile and was further modified to expand the structure–activity relationship of the chemotype, develop additional analogs, and optimize potency, bioavailability, and in vivo efficacy. Ten new lead variants were generated. Of those, Qx-294 and Qx-301 demonstrated promising in vitro Absorption, Distribution, Metabolism, and Excretion (ADME) profiles and were selected for further testing. Overall, both compounds were rapidly absorbed in zebrafish and mice and promoted cell proliferation in vitro and in vivo without signs of apoptosis, supporting their potential for sensory HC regeneration.